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4 Using the Regenerative Power System
Current Sinking Operation
Current/Power Sinking
Regenerative Operation
Current/Power Sinking
Current/power sinking, also referred to as down-programming, is the ability to pull current into the
positive terminal of the power supply. For example, the power supply pulls or sinks current into the
positive terminal whenever a lower output voltage is programmed. This is necessary because stored
energy from the power supply's output capacitor and external capacitance from the load, including the
wiring, must be discharged to lower the voltage at the output terminals.
The ability to rapidly transition from a higher to a lower constant voltage level greatly improves the
power supply's output response time. At some point, some of this energy may be returned to the ac
mains by the power supply. This is the most commonly used application of the regenerative function of
the unit, which is automatic and completely transparent to the user.
The power supply can also continuously sink up to 100% of its rated current/power for an indefinite
time. This
two-quadrant
sourcing and sinking capability of the power supply allows for seamless
transitions between sourcing and sinking current/power without changing the power supply's output
characteristics or introducing any disruptive behavior. The following controls are provided to fully
utilize the two-quadrant output capability of the supply.
Current Limit control in voltage and power priority mode
When operating in voltage or power priority mode, you can program a negative and positive
current
limit. This will limit any current overshoots that may occur during rapid up- or down-programming.
Current setting control in current priority mode
When operating in current priority mode, you can program the output current to seamlessly cross the
zero point when transitioning from positive to negative or negative to positive. Additionally, when
operating in the negative current quadrant, you can program a negative
current setting
that will hold
the sink current at the specified value. This is useful, for example, for discharging a battery at a
constant current rate.
If your application requires precise control of the sourcing and sinking current, current
slew controls
are available to specify a current slew rate when sourcing and sinking current.
Power setting control in power priority mode
When operating in power priority mode, you can program the output power to seamlessly cross the
zero point when transitioning from positive to negative or negative to positive. Additionally, when
operating in the negative power quadrant, you can program a negative
power setting
that will hold the
sink power at the specified value. This is useful, for example, for discharging a battery at a constant
power rate.
Keysight RP7970 & RP7980 Series Operating and Service Guide
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